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Can a car cary enough solar panels / Can solar panels carry enough to charge an electric car?

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  • 505HPC6Z06
    replied
    Every leaf owner I've talked to (10+ owners) says they have a range of about 70 miles. No where near the 100 mile manufacturer claim.

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  • 505HPC6Z06
    replied
    Originally posted by LETitROLL View Post
    This is a direct quote from chevy's website (2016 volt, not sure if prior years are same),

    "using the 120 volt portable charger will take approx. 19 hours at the default 8 amp setting and can be reduced to 13 hours at the 12 amp setting"

    it appears you can recharge one of these cars (slowly)(very slowly) from a standard 120v outlet drawing either 8 or 12 amps, it does not take that tremendous of a solar system to replicate one household outlet. So it appears it is possible (still not financially or environmentally wise) to do this, especially if during sun hours only, one could limit battery (to satisfy CC) to something reasonable if you were not trying to store a lot of energy for use later at night, etc.

    And if anyone mounts solar panels on their house and runs the wires inside to a live outlet, it doesn't matter if you run a light bulb in the kitchen or plug your car in the garage, you would be completely justified and legal (my .02) taking the Tax Credit (talk to your cpa).

    Not saying attempting any of that is at all smart or that i would do it (i wouldn't), but if the 120v chargers work at all it is doable (would take 2 days worth of sun)
    Another benefit to using solar with the 120v charge cord is having the car plugged in when not in use. It may take 2 days for solar to charge the car, but the Volt owners manual and probably the OP's owners manual in the Spark states the battery is conditioned when plugged in and that prolongs the battery life.

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  • jflorey2
    replied
    Originally posted by Sunking View Post
    No one's efficiency is as high as Tesla at roughly 160wh/mile. The 250 wh/mile you quote is no where near that good.
    From a Tesla forum:

    "Over at Tesla Motor Club there is a thread lifetime Wh per mile., that gives a good range what to expect. My lifetime average for 6k miles is 335 Wh / m... but that includes a lot of city, on longer trips I can easily get it under 300 Wh / m driving 72-75 m/hr."

    300-320 is about average for a Tesla. 250-300 is about average for a Leaf.

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  • jflorey2
    replied
    Originally posted by Richard808 View Post
    Here is what you have not thought about, because you are not listening: The battery is in the car. Got that? It's the big heavy thing in the bottom of the little cute car that makes the little car ride like a 1948 Cadillac. 10-4
    I once test drove a Leaf, and while I was in the lobby another guy there was also waiting to test drive one and was telling everyone what he would do. "I'll just put a solar panel on top and charge the car for free!" He then paused, perhaps waiting for the polite applause that must inevitably follow any such a brilliant pronouncement. He didn't get any applause but he did get some very appreciative looks from the salesmen; you could tell they were thinking "we got him."

    Here's what you don't get - you just won't get much solar power from a car sized array. A large car has about two square meters of solar space on the roof and hood. The sun (that's that big bright thing you see during the day; go check it out) sends the Earth 1366 watts of energy per square meter every day. "Great!" a solar newbie might say. "That's 32 kilowatt-hours of sun a day. I can charge my Leaf 100% during the day!"

    They might even try it. Then reality will begin to creep in, as it always does.

    First the atmosphere takes its toll. That 1366 watts becomes about 1000 (if you are lucky.) Then you realize that the best commercial panels have an efficiency of about 18%. Then you further realize that even though it's sunny 12 hours a day, you get the equivalent of only about 5 hours of direct sunlight depending on where you are. Now your 32 kilowatt-hours has become 1.8 kilowatt-hours; about enough to get 7 miles of range a day.

    OK maybe you can live with that.

    Then you try it - you bolt two big panels to the car; one on the roof and one on the hood. You realize that it looks pretty ugly, but you're willing to live with that. Next you have to connect to the batteries. This is a bigger problem; EV's are designed to isolate the battery from the rest of the car when it's off, and has several mechanisms to shut off battery power if it sees unexpected current flows (such as from a solar charger.) You hack and hack, and finally manage to defeat all the protections and get access to the battery terminals. You've now connected to the battery! Yay! You will never be able to get the car serviced under warranty again, but you are a pioneer, so don't worry about it.

    But now you have a new problem. Your panels are generating between 12V and 60V, and your batteries charge at voltages between 360 and 400 volts. So now you need a boost converter - and 12V to 400V is an unusual voltage you won't be able to get off the shelf. You call Genasun and they don't make anything like that, but they point you towards a custom engineering house that can build you one.

    OK, so now you are around a thousand dollars poorer - but you have a custom built one-off boost converter capable of boosting 12 to 36 volts to 400 volts at powers of about 400 watts. You hook it up, expose the panels to the sun, and something happens! But it's not what you expect. The panel voltage, which should be around 36 volts, is hovering around 5 volts and you're delivering about 40 watts to the battery. What happened?

    You realize after a bit more research that you need a peak power point tracker to match the impedance of the converter to the impedance of the panels. So it's back to the engineering house to build you one of those. A clever guy there manages to build a very simple one for another thousand dollars of engineering time. You hook it up and now the panels are at about 30 volts and you're delivering 300 watts to the battery! Not the 360 watts you expected, but that's the difference betwen theory and real world.

    So you cable-tie everything together and you proudly get on the freeway to drive the 10 miles to work. You're a solar pioneer! You are going to tell the power company and the oil company to shove it! You get to work . . . and you realize you've used almost twice the power you expected. Turns out those panels are draggy. You now need to make up 3 kilowatt-hours instead of 1.8.

    So you park it there all day. And when you get back to your car, you hop in and fire it up, hoping to bask in the solar glow of your free driving range. And instead of getting the 3 kilowatt-hours, you got less than 1 - about two miles of range. Turns out there was a power line above the parking lot you never noticed before, and even that amount of shadow was enough to reduce your system's output by over 50%.

    But you soldier on and drive home.

    And after a few days of this you realize you have to charge even more than you did before, because the drag penalty is greater than the half a kilowatt-hour or so you get on a sunny day in that parking lot. Then one day you have to go to the mall and the only parking spot is in an underground lot . . .

    So now you're frustrated. You KNOW you are smarter than all those idiots on the solar forums, and you are going to make this work, dammit! So you get a quote from the engineering house (who is really digging all the money you are sending their way) for integrating the solar panel into the car into an areodynamic form-hugging assembly. You get the quote for that, check out your dwindling bank account, and think perhaps there's another way to do this.

    "Aha!" you say. "I will just install stationary solar arrays at home and at work and charge that way! No drag or weight penalty! And with a good install, no shadows or overhangs. I'll show those idiots on line and still tell the power company to shove it." So you price out what it will cost to build arrays at home and work to produce a few kilowatts. But you don't want to deal with another boost converter debacle, so you decide to size the array to produce 400 volts nominally. You price it out and get quotes for both arrays. At $3.50 a watt (a pretty good price for a nonstandard array) you'd be looking at a 2kW system for around $6000. Times two.

    So you install the first system and connect it directly to your car. You have chosen the peak voltage (STC DC) to be around 400 volts, so you don't need a charge controller or boost converter. And for a few days it works OK. Then one cold morning the sun comes up, and due to the low temperature and a high SOC of your battery pack, you see an array voltage of 460 volts. Ordinarily the battery's BMS would disconnect the battery to protect against overcharge, but remember how you had to "wire around" that to get the battery to connect to your charger? Instead of the BMS protecting the battery, you overvoltage the battery and destroy it.

    You take the car to the dealer and they laugh at you when you ask them to fix it. You finally bargain with them and come to an agreement - they'll charge you $5000 for a new battery and $2000 to fix the mess you made off the rest of the system.

    Now you're back to square one. You start to think perhaps there is some value in using the EV system as it was designed - using the car's charger and battery protection system. Yeah, maybe it's an example of "the man keeping you down" but your first attempts were pretty expensive. So you think of ways to charge using the on-board charger. It takes 240 volts. And you realize, in a sudden flash of insight, that grid tie inverters GENERATE 240 volts! It sounds like a match made in heaven.

    But then you realize a new problem. Drive your car 100 feet and look underneath. Now find the battery. (Should be easy to find; you just paid $5000 to replace it.) You'll note to your dismay that the battery WENT WITH THE CAR! Get it? It won't stay conveniently near a charger. That means you have a few choices:

    1) Get a 10 mile long extension cord and drag it behind the car.

    2) Install two systems (one at work, one at home) at double the cost. And they might not want you to do that at work.

    3) Find some company out there who will deliver power from point A to point B for you for a nominal charge. A company that, perhaps, will charge you a nominal fee to accept your power and deliver it to another location. They might even accept more power than you use (say, from your home system while you are at work on days you don't drive as far) and GIVE YOU MONEY for it! This means your investment in your solar array will always be making power for you, and you'll get far more bang for your buck.

    Once you reach this point, years later and thousands of dollars poorer, then _you_ will become one of those "old fogy" jerks on forums like this who tell people they are making a mistake.

    Leave a comment:


  • LETitROLL
    replied
    Originally posted by DerGiLLster View Post
    GUYS, I don't care if I will charge with solar panels all the time. Just some of the time. I don't expect to charge the full battery with solar panels, just enough for a day's trip.

    Is it too much to ask for an inverter being 15-20 KW at MAX just so it can charge around 40-50 miles for me? Could it be with multiple smaller inverters?

    I don't care if some days I use panels while some I will use from the grid. I just want to have some charging for free and for environmental reasons.
    This is a direct quote from chevy's website (2016 volt, not sure if prior years are same),

    "using the 120 volt portable charger will take approx. 19 hours at the default 8 amp setting and can be reduced to 13 hours at the 12 amp setting"

    it appears you can recharge one of these cars (slowly)(very slowly) from a standard 120v outlet drawing either 8 or 12 amps, it does not take that tremendous of a solar system to replicate one household outlet. So it appears it is possible (still not financially or environmentally wise) to do this, especially if during sun hours only, one could limit battery (to satisfy CC) to something reasonable if you were not trying to store a lot of energy for use later at night, etc.

    And if anyone mounts solar panels on their house and runs the wires inside to a live outlet, it doesn't matter if you run a light bulb in the kitchen or plug your car in the garage, you would be completely justified and legal (my .02) taking the Tax Credit (talk to your cpa).

    Not saying attempting any of that is at all smart or that i would do it (i wouldn't), but if the 120v chargers work at all it is doable (would take 2 days worth of sun)

    Leave a comment:


  • Sunking
    replied
    Originally posted by jflorey2 View Post
    Think you've got that backwards. An efficient EV (like a Leaf) driven conservatively will use 1 kilowatt-hour every 4 miles; that's why it's 24khwr pack gives it a range of almost 100 miles. A less efficient EV (like a Tesla) driven aggressively is more like 1 kilowatt-hour every 2 miles.
    No one's efficiency is as high as Tesla at roughly 160wh/mile. The 250 wh/mile you quote is no where near that good.

    Leave a comment:


  • jflorey2
    replied
    Originally posted by 505HPC6Z06 View Post
    It would be an educated guess since that data isn't available to me. Using a low of 2kWh and a high 4kWh for energy used per mile, for 6.4MegaWh used the miles driven would be 25,944 mi. or 12,972 mi.
    Think you've got that backwards. An efficient EV (like a Leaf) driven conservatively will use 1 kilowatt-hour every 4 miles; that's why it's 24khwr pack gives it a range of almost 100 miles. A less efficient EV (like a Tesla) driven aggressively is more like 1 kilowatt-hour every 2 miles.

    Leave a comment:


  • 505HPC6Z06
    replied
    Originally posted by J.P.M. View Post
    One other piece of information or fun fact that this old solar fogy is curious about is the # of miles driven for that 6,486 kWh of consumption. Sounds like that's maybe /not possible. Now, back to my Alzheimer's support group - if I can remember where I left them.
    It would be an educated guess since that data isn't available to me. Using a low of 2kWh and a high 4kWh for energy used per mile, for 6.4MegaWh used the miles driven would be 25,944 mi. or 12,972 mi.

    I'm in S. California now and it is a much better environment for electric cars because of the mild temperature and lack of need to heat the cabin. Here it is about 2kWh off-freeway driving (or less than 55 MPH). In WA state where I spent 2013, energy per mile would be closer to 4 kWh per mile because I needed the heater and my commute had more hills to climb.

    Leave a comment:


  • Living Large
    replied
    Originally posted by Richard808 View Post
    Some of the replies on this thread indicate -- no, prove -- that one can become a solar old fogy.
    And some of the comments in this thread would seem to indicate that pigs can fly with a couple of solar panels strapped to their backs.

    Leave a comment:


  • J.P.M.
    replied
    Originally posted by 505HPC6Z06 View Post
    Chargepoint is an EV charging network and I have been using from time to time since 2012 for public charging of my Volt. They collect usage data and give their customers reports on that data. To put things in perspective and for fun facts, the Volt used 6.4 MegaWh or 6,486 kWh since then. January 2013, 375 kWh was used. It would be interesting to share a total number from all networks and residences, maybe the car has that data but I don't have access to it.
    One other piece of information or fun fact that this old solar fogy is curious about is the # of miles driven for that 6,486 kWh of consumption. Sounds like that's maybe /not possible. Now, back to my Alzheimer's support group - if I can remember where I left them.

    Leave a comment:


  • SunEagle
    replied
    Originally posted by 505HPC6Z06 View Post
    Chargepoint is an EV charging network and I have been using from time to time since 2012 for public charging of my Volt. They collect usage data and give their customers reports on that data. To put things in perspective and for fun facts, the Volt used 6.4 MegaWh or 6,486 kWh since then. January 2013, 375 kWh was used. It would be interesting to share a total number from all networks and residences, maybe the car has that data but I don't have access to it.
    Interesting data on your Volt. It would be nice to see data concerning the charge/discharge profiles of specific EV's.

    Maybe Chevy has that data so they can understand the issues (if any) of their product to make improvements.

    Leave a comment:


  • 505HPC6Z06
    replied
    Chargepoint is an EV charging network and I have been using from time to time since 2012 for public charging of my Volt. They collect usage data and give their customers reports on that data. To put things in perspective and for fun facts, the Volt used 6.4 MegaWh or 6,486 kWh since then. January 2013, 375 kWh was used. It would be interesting to share a total number from all networks and residences, maybe the car has that data but I don't have access to it.

    Leave a comment:


  • J.P.M.
    replied
    Originally posted by SunEagle View Post
    Or maybe some people understand the science and physicaly limitations of how much power a vehicle needs to move compared to what a solar panel can generate.
    You beat me to it.

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  • SunEagle
    replied
    Originally posted by Richard808 View Post
    Some of the replies on this thread indicate -- no, prove -- that one can become a solar old fogy.
    Or maybe some people understand the science and physicaly limitations of how much power a vehicle needs to move compared to what a solar panel can generate.

    Leave a comment:


  • Richard808
    replied
    Solar fogies

    Some of the replies on this thread indicate -- no, prove -- that one can become a solar old fogy.

    Leave a comment:

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